Mosquitoes are perhaps the most important disease vectors known to humankind; hence a great deal of effort is directed towards elucidating novel, efficient and safe means to control them. This is particularly important given the advent of mosquito stains which are increasingly resistant to many commonly used insecticides. The use of mosquitocidal toxins produced by Bacillus thuringiensis subsp. israelensis (Bti) is an attractive means of markedly increasing the available repertoire of control agents, particularly when used in concert with other control strategies. Bti toxins are environmentally saf e, as demonstrated in numerous studies, showing virtually no toxicity to non-target invertebrate as well as vertebrate species. In addition, these toxins act at very low levels, in the nanogram/ml (ppm) range. Unfortunately, Bti toxin preparations are considerably more expensive than chemical pesticides and have a relatively short half-life in the field, resulting in higher applications costs. We propose to increase the half life of Bti toxin formulations and possibly lower production costs by producing the toxins within a cyanobacterial cell. Several approaches aimed at increasing toxin expression in a cyanobacterial host will be utilized. In addition, we feel this work will have applications toward the expression of other valuable proteins in cyanobacteria. PROPOSED COMMERCIAL APPLICATION: Beyond producing a mosquitocidal cyanobacterial strain with increased half life in the field, this research should be applicable to the production of other recombinant proteins in cyanobacteria.